L3: oral histology

Question 1

what are the 3 layers of epithelium in non keratinized oral mucosa

Answer 1

outermost to innermost:
superficial
intermediate layer
basal layer

Question 2

what are the 4 layers of epithelium in keratinized mucosa

Answer 2

outermost to innermost:

corneal layer (stratum corneum)
granular layer (stratum granulosum)
spinous layer (stratum spinosum)
basal layer (stratum basale)

Question 3

what is the difference between ortho and para keratinized epithelium

Answer 3

para keratinized got flattened cell nuclei
ortho dont have

Question 4

what are rete ridges

Answer 4

are epithelial projections into lamina propria

Question 5

2 kinds of lamina propria

Answer 5

papillary, reticular

Question 6

what are papilla in the lamina propria

Answer 6

connective tissue projections into epithelium

like interdigitate with rete ridges

Question 7

defn of hyperkeratosis

Answer 7

thickening of stratum corneum

Question 8

defn of epithelial hyperplasia aka acanthosis

Answer 8

characterized by increased cell numbers, which usually results in increased thickness of the squamous epithelium

Question 9

when there is an increase in spinous layer cells, it is called

Answer 9

acanthosis

Question 10

what is epithelial atrophy

Answer 10

thinning of epithelium associated with decrease in number of epithelial cells

Question 11

what can counting mitotic figures tell a pathologist

Answer 11

can help to tell benign from malignant or a change towards malignancy

Question 12

what are mitotic figures

Answer 12

microscopic appearance of a cell undergoing mitosis
instead of a nucleus, chromosomes are visible as tangled, dark staining threads

Question 13

normal mitosis always happens in which layer in epithelium

Answer 13

basal

Question 14

in epithelial dysplasia, what happens to nucleus

Answer 14

nuclear size increases leading to increased N:C

Question 15

what does hyperchromatic nuclei mean and what is it indicative of

Answer 15

dark, strongly stained nucleus
(indicative of proliferative status)

Question 16

compared to the cells in other layers, basal cells have what kind of nuclei and cytoplasm. as it moved up the layers, what happens?

Answer 16

• basal cells have bigger, darker nuclei and smaller cytoplasm
• as it moves up, nucleus becomes smaller, cytoplasm becomes bigger
• cell flattens out

Question 17

___ hold keratinocytes together

Answer 17

desmosomes

Question 18

what does endophytic vs exophytic mean

Answer 18

• endophytic = lesion that appears to grow inwards into underlying tissues (invasive properties, usually more dangerous)
• exophytic: lesion that appears to grow outwards from mucosa

Question 19

what are the 7 stages of tooth development

Answer 19

1) initiation
2) thickening of dental epithelium
3) bud stage
4) cap stage
5) early bell stage
6) late bell stage
7) root formation stage

Question 20

in the bud stage, the _____ resembles a small bud

Answer 20

enamel organ

Question 21

what type of cells form enamel organ?

Answer 21

peripherally located low columnar basal cells
centrally located polygonal cells

supporting ectomesenchymal cells are packed closely beneath and around the epithelial bud

Question 22

in the cap stage, what types of differentiation give rise to 3 cell types

Answer 22

histo and morpho differentiation

Question 23

in the cap stage, what is the description of the peripheral cells?

Answer 23

cuboidal, they line the convexity
known as the OEE

Question 24

in the cap stage, what are the 3 cell types formed?

Answer 24

OEE -> peripheral cells, cuboidal
IEE -> cells lining concavity, columnar
stellate reticulum -> body of the cap shaped ename organ is filled with loose star shaped cells

Question 25

in the early bell stage, what cells is the IEE made of

Answer 25

short to tall, columnar cells (pre ameloblasts)

Question 26

in late bell stage, what does IEE differentiate into

Answer 26

IEE in the early bell stage was columnar cells (pre ameloblasts), late bell: differentiate into enamel secreting cells (ameloblasts)

Question 27

what cells are in the odontoblastic layer of the dental papilla

Answer 27

tall, columnar shaped

Question 28

what is the layer of cells between the IEE and the stellate reticulum called what shape are they

Answer 28

stratum intermedium compressed flat to cuboidal cells

Question 29

which phase is the reduced enamel epithelium found in

Answer 29

pre eruptive phase

Question 30

what happens in pre eruptive phase

Answer 30

enamel organ collages and reduces to few layer thick epithelium called reduced enamel epithelium REE = compressed stratified squamous epithelium derived from compression of ameloblasts, SI and SR, OEE layers

Question 31

what epithelium is common in a cyst associated with inflammation?

Answer 31

non keratinised stratified squamous epitelium with rete ridge formaiton

Question 32

dentigerous cyst originates from what

Answer 32

from odontogenic apparatus

Question 33

we have as many enamel organs as we have ___

Answer 33

teeth

Question 34

what does ameloblastoma mean

Answer 34

means the px has many many enamel organs, not just the number that corresponds to the number of teeth

Question 35

what types of cells are in the epithelial islands of a ameloblastoma?

Answer 35

peripheral palisading of tall columnar basal cells and star shaped stellate reticulum-like cells in the centre of the island

Question 36

osteoblasts are derived from what

Answer 36

osteoprogenitor cells

Question 37

what are osteocytes

Answer 37

inactive osteoblasts that have become trapped within the bone they have formed

Question 38

features of osteoclasts - derived from ___ - break down bone matrix through ________ - single or many nuclei? - space between osteoclast and bone is known as ____

Answer 38

- derived from monocytes aka macrophages - break down bone matrix through phagocytosis - multinucleated cells - space between osteoclast and bone is known as Howship's lacuna

Question 39

what is the composition of bone matrix

Answer 39

osteoid and calcium hydroxyapatite osteoid = unmineralized matrix composed of type 1 collagen and GAGs calcium HAP = calcium salt crystal that gives bone its strength and rigidity

Question 40

what are the 2 types of bone

Answer 40

1) compact/ cortical bone 2) trabecular bone aka cancellous/spongy bone

Question 41

what is the function of compact bone what attaches to it

Answer 41

- mainly mechanical function - is the area of bone to which ligaments and tendons attach - is thick and dense

Question 42

what is the function of trabecular bone and where is it located?

Answer 42

mainly metabolic function located between layers of compact bone is thin and porous also located within trabeculae is the bone marrow

Question 43

where is compact bone usually seen

Answer 43

mostly in flat bones or outermost layer of long bones

Question 44

compact bone is composed of ___, which are arranged _____ around _____. these areas are called _____

Answer 44

compact bone is composed of lamellae, which are arranged concentrically around Haversian canals. these areas are called osteons

Question 45

what type of bone is lamina dura

Answer 45

compact (only that part is compact, the rest of the alveolar bone is cancellous)

Question 46

cancellous bone is composed of _____ of bone that form an ________ within the bone. the spaces between trabeculae is filled by either _____ or ______. are haversian system present in the trabeculae?

Answer 46

cancellous bone is composed of trabeculae of bone that form an interconnected meshwork within the bone. the spaces between trabeculae is filled by either red bone marrow or yellow bone marrow. no, not present

Question 47

what is woven bone

Answer 47

early bone matrix (osteoid) with many osteocytes and a disorganized matrix structure

Question 48

woven bone is eventually replaced by _________

Answer 48

lamellar bone

Question 49

in histo, what colour is woven bone?

Answer 49

lighter pink than the mature bone

Question 50

osteoclasts lie within concavities known as ____ or ____

Answer 50

howship's lacunae or resorption bays